This disclosure relates to a stuffing box to sealingly engage with a rod member that passes therethrough. More particularly, this disclosure relates to a stuffing box suitable for oilfield operations to sealingly engage a pump rod extending to a downhole pump, and to improved packing rings for use within a stuffing box.
Stuffing boxes are used in various applications for sealing with a rod-like member that passes through the stuffing box and either reciprocates or rotates relative to the stuffing box during operations. The stuffing box sealingly engages with the rod member to retain fluid pressure, thereby allowing the rod member to extend through the stuffing box and into a sealed chamber, which is typically fluid pressurized. A plurality of axially stacked packing rings or packing glands seal between the body of the stuffing box and the reciprocating or rotating rod member. The packing rings are axially compressed or loaded by adjusting a gland member that is moveable relative to the stuffing box body, thereby exerting a compressive force on the packing rings to result in enhanced sealing. If the stuffing box leaks, the gland member may be tightened to increase the loading on the packing rings, thereby re-sealing the packing rings with the rod member. Packing rings or packing glands of the stuffing box are thus distinguishable from conventional seals, which generally are not provided in a stacked arrangement, are not axially compressed by mechanical forces, and cannot be intermittently loaded to vary sealing effectiveness.
In oilfield operations, stuffing boxes are typically used to seal a reciprocating or rotating rod string (or more particularly with a polished rod of a rod string) that in turn drives a downhole pump. In addition to oilfield operations, stuffing boxes are widely used to seal with rotating and/or reciprocating valve stems for various types of valves, and to seal with rods or pistons of pumps and other equipment that generate or handle pressurized fluid.